I picked up a pack of these on Amazon the other day, and so far they work great. Easy to pick up and move, fun to mess around with. So far I've just been grabbing a fistful and numbering them ("Here are six cultists, or four troglodytes, or...") but when we get to a point with more mixed encounters I might combine with your method and start gluing faces to the faces.
I've been using some wooden tokens like these. I also got a small woodburning tool and a lettering set to mark them.
I got some wooden tokens on Amazon and then made a template in Photoshop to drop artwork into. Then I print off a full sheet on card stock, punch them out, and glue them onto the tokens. They're relatively cheap and thick enough that I can easily pick them up without them sliding around. All of the tokens also have a number on them which helps me keep track of health and when my players tell me which they're attacking.
1" Tokens here for Small/Medium Monsters
2" Tokens for Large Monsters
I haven't had my party fight anything larger yet but I like the idea of butter/yogurt tubs for the larger enemies.